undercover science... codemaking & breaking
So, you’re passing a note involving Ms Andrews the Maths teacher. If you’re sure she won’t catch you - go ahead and write it in plain English!
But you know what she’s like, eyes in the back of her head and all that, also she KNOWS that you, being a pupil, will be trying to communicate with your mates when you should be knuckling down to her fascinating equations.
What you need to do is code your message, so even if she does intercept it, it won’t mean a thing to her. You can tell her it’s actually about your work and you might even be able to impress her with your ciphering ability!
Now, imagine Ms Andrews is an enemy state or a competitive company, and you are the British Secret Service or your company’s Research and Development Team. You still need secrecy, you still need to send coded messages. But the stakes are higher…
In the past, codes were mostly needed to protect information about transfers of trade and military information. Today, another key use for encryption is on the internet – to keep credit card information secure.
One thing is certain - codes and ciphers are still just as much part of everyday life as they were hundreds of years ago. And as time goes on, the ciphers get more and more ingenious…
operation: coded message
In sending a secure message, your first assumption must be:
Your message will be or has already been intercepted.
Your objective is therefore:
To make it impossible – or at any rate supremely difficult and time-consuming – for the interceptor to decrypt the intercepted message.
how ciphers work: meet alice & bob
In the encryption business, there are three famous characters.
Alice (A) and Bob (B) – who are trying to send a message between them securely.
And there’s a third person they talk about: Eve (E). Eve’s the one who’s trying to intercept and read the message.
There’s the message you’re trying to send or receive.
And there’s the key. The key is the recipe by which the message is scrambled … and the receiver needs the key to be able to unscramble it.
So Alice needs to make sure that Bob not only gets her message, but also has the correct key to be able to read it. And while the message can be intercepted by others, it’s crucial that the key cannot.
Here are three famous ciphers you can try for yourself:
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